Plasma is typically an ionised gas. The term “ionised” refers to presence of free electrons, which are not bound to an atom or molecule. The free electrons make the plasma conductive so that it responds strongly to electromagnetic fields.
Plasma is commonly used in plasma displays (including TVs), fluorescent lamps (low energy lighting), neon signs, fusion energy research, electric arc in an arc lamp, arc welder or plasma torch, etch dielectric layers in the production of integrated circuits. Usually plasma is generated by a periodical signal (for example a sinusoidal signal). But in this case the generation can be controlled (triggered in a single shot for example).
Among the new plasma technology applications, plasma for medicine and biology are the most rising. The demonstration of spectacular effects in the treatment of diseases of the skin or very encouraging results on changes in the behaviour of the tumor cells are in the process of literally explode research in this area, like all processes concerning the processing of materials in the framework of the implementation of biocompatible surfaces. For these reasons, there is an increase interest for generation of atmospheric plasma plumes or “needles” for use in sterilization and decontamination, skin and tumor treatment, or dental care. In most cases the discharge device generating the plasma medium is at short distances of several centimeters or very close to the surface to be treated due to plasma production (direct DBD) or due to the rather rapid extinction of the plasma plume travelling in air.